Summary of Significant Accounting Policies - Schedule of Recurring Assets and Liabilities Measured at Fair Value (Detail) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Level 1 [Member] \| Unsecured Notes [Member]
Derivatives Fair Value [Line Items]
Debt instruments measured at fair value	$ (25,790,000)
Level 2 [Member] \| Interest Rate Cap [Member]
Derivatives Fair Value [Line Items]
Interest rate cap	207,859	$ 5,213
Level 2 [Member] \| Interest Rate Swap [Member]
Derivatives Fair Value [Line Items]
Interest rate cap	(150,097)
Level 2 [Member] \| Mortgage Loans [Member]
Derivatives Fair Value [Line Items]
Debt instruments measured at fair value	$ (360,293,427)	$ (292,368,370)

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

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+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

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+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

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-Name Accounting Standards Codification
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